Stephens was walking with several others in the 5700 block of South Morgan as they left a holiday party, when he and two other teens, a boy, 16, and a man, 19, were shot.

Anthony Walter, 20, was charged with murder in Stephens' slaying in February. At the time, prosecutors said Walter was one of several people who participated in the shooting,

Prosecutors said Walter was not the shooter, but that he supplied to the weapon to the would-be attacker who was still being sought by police.

Parker, who already was in Cook County Jail on an unrelated charge, was arrested Tuesday in connection with Stephens' slaying and charged with murder about 1:20 a.m. Wednesday, police said. It was not clear whether prosecutors allege he fired the fatal shots, and police did not make public the charges against him until after he appeared in Cook County Central Bond court Wednesday.

Parker and Walter were both being held without bail at Cook County Jail.